Lubricant compositions

ABSTRACT

THE OXIDATION AND EXTREME PRESSURE PROPERTIES OF LUBRICATING OILS ARE IMPROVED BY ADDING THERETO A COMPOUND PREPARED FROM CETYL VINYL ETHER AND N-VINYLPYRROLIDONE IN THE PRESENCE OF A TRIHYDROCARBYL PHOSPHITE.

3,663,439 LUBRICANT COMPOSITIONS Gerassimos Frangatos, Westmont, N.J., assignor to Mobil Oil Corporation N Drawing. Filed June 25, 1970, Ser. No. 49,939 Int. Cl. Cm 1/44 US. Cl. 252-493 10 Claims ABSTRACT OF THE DISCLOSURE The oxidation and extreme pressure properties of lubricating oils are improved by adding thereto a compound prepared from cetyl vinyl ether and N-vinylpyrrolidone in the presence of a trihydrocarbyl phosphite.

BACKGROUND OF THE INVENTION Field of the invention This invention relates to lubricating oils having desirable oxidative and extreme pressure properties. The invention relates more particularly to the improvement of such lubricating oils by incorporating therein additives which are effective in improving the oxidative stability and extreme pressure properties of such oils.

Description of the prior art Lubricating oils are subject to oxidative deterioration at elevated temperatures or upon prolonged exposure to the elements. These lubricants, including mineral oils and synthetic oils, undergo oxidative deterioration in service, especially at high temperatures. This deterioration produces sludges and gums, causes metal parts to corrode and produces loss of lubricating properties of the oil. Many additives of the prior art are only marginally effective except at high concentrations, especially when the oils are subjected to drastic oxidizing conditions.

SUMMARY OF THE INVENTION In accordance with the present invention there is provided a lubricating oil composition comprising a major amount of oil and an amount sufficient to impart stability properties thereto of a compound produced by reacting together cetyl vinyl ether, N-vinylpyrrolidone and a trihydrocarbyl phosphite. The latter compound acts as a telogen in the copolymerization of the two vinyl mono mers. A telomer is thus obtained.

DESCRIPTION OF SPECIFIC EMBODIMENTS The aforementioned product may be made using molar ratios of the cetyl vinyl ether and N-vinylpyrrolidone monomers of from about 1:1 to about 1:20 to 20: 1. Preferably such ratio will be 1:1. The trihydrocarbyl phosphite is used in an amount equal to or larger than the molar concentration of the monomer present in the higher concentration. If the trialkyl phosphite is in excess, this excess will generaly range from about 10 to about 30%. Preferably, however, such excess should not exceed about 20%.

The product is made up of recurring units of copolymerized vinyl monomers, terminated with a phosphorus moiety linked to such copolymer through direct linkage with the phosphorus atom. More precisely, it is believed that the structure of the telomer will conform to the following representation.

3,663,439 Patented May 16, 1972 wherein 11 may vary from about 2 to about 200 and R is a hydrocarbyl group as hereinafter defined.

In general, the invention contemplates the use of from about 0.005 to about 15% of the additive in lubricating oils. Preferably, the concentration of additive in such oil will be from about 0.01 to about 10% by weight thereof, more preferably from about 1.0% to about 5.0%.

The lubricants which may be improved by the addition thereto of the above-mentioned copolymer are mineral oils, both parafiinic and naphthenic, and synthetic oils. The synthetic oils include polyolefin fluids, polyglycols, polyacetals, the siloxanes and the like. Especially useful are those synthetic esters which are becoming more and more popular, particularly in aviation. These include esters made from polycarboxylic acids and monohydric alcohols, such as those obtained by reacting methanol, ethanol, propanol, butanol, neopentyl alcohol and the like with pimelic acid, azelaic acid, adipic acid and the like, or from polyhydric alcohols and monocarboxylic acids. Of these preferred members are those made from trimethylol alkanes, where alkane includes ethane, propane and butane, pentaerythritol, diand triphentaerythritol, or mixtures thereof and an aliphatic monocarboxylic acid containing from 1 to about 20 carbon atoms or a mixture of such acids. The most preferred are esters from the pentaerythritols and monocarboxylic acids having from 5 to 9 carbon atoms, or mixtures of these acids.

In general, the products contemplated herein may be prepared by blending the cetyl vinyl ether, N-vinylpyrrolidone and trihydrocarbyl phosphite in an inert organic solvent and heating in the presence of a free radical initiator for the time required to complete the reaction. In general, the temperature of reaction will depend upon the half-life of the free radical source used as the initiator of the polymerization reaction. More specifically, the reaction may be effectively carried out at temperatures within the range of from about 50 C. to about 200 C. Reaction times will range from about 1 hour to about 20 hours.

Any of the well-known solvents may be used in preparing the product. One example of useful solvent is chlorobenzene. Others include benzene, toluene, xylene, mesitylene, dioxane, and carbon disulfide.

Any of the commonly used initiators may be employed in the practice of this invention. Most common among these, and the preferred ones, are the peroxides and hydroperoxides. These include ditertiary butyl peroxide, dibenzoyl peroxide, dilauryl peroxide, diacetyl peroxide, dicumyl peroxide, tertiary butyl hydroperoxide, methyl ethyl ketone hydroperoxide, cumyl hydroperoxide, azoisobutyronitrile and percarbonate esters.

The trihydrocarbyl phosphites include those wherein each hydrocarbyl portion contains from 1 to about 20 carbon atoms. Preferably among these are those phosphites having lower alkyl groups, i.e., those of from 1 to about 6 carbon atoms. Specifically, there may be mentioned the trimethyl, triethyl, tributyl, and trihexyl phosphites and the alkyl portions thereof may be straight or branched chain. The hydrocarbyl group of the phosphite may also be an aryl, such as phenyl or naphthyl, an alkaryl, such as tolyl or ethylphenyl, or an aralkyl such as benzyl or phenethyl.

The following examples will serve to specifically illustrate the practice of the invention. It will be understood that they are illustrative only, and are not intended to limit the scope of the invention to a narrower range than described hereinabove.

EXAMPLE 1 Into a reaction vessel equipped with a condenser, stirrer and thermometer was placed a mixture of 83.1 grams (0.5 mole) of triethyl phosphite and 200 m1. of ch1oro benzene and the temperature thereof brought up to reflux (about 130 C.). 44.4 grams (0.4 mole) of N-vinylpyrrolidone, 107.2 grams (0.4 mole) of cetyl vinyl ether and grams of ditertiary butyl peroxide were placed in 200 ml. of chlorobenzene, and this mixture was added to the refluxing chlorobenzene over a period of 1 /2 hours 'With stirring, under a nitrogen atmosphere. Heating at 125-130 C/was continued for a period of 10 hours. An additional 5 grams of ditertiary butyl peroxide was added and heating at 125130 C. was continued for another 4 hours. The solvent and unreacted monomers were distilled off under reduced pressure and finally at 0.6 mm. of Hg at 240 C. The product, 128 grams, was a clear viscous fluid. An analysis of this product showed it to contain 0.88% of phosphorus and to have a molecular weight of 1232.

EXAMPLE 2 Evaluation of products Oxidation test in synthetic ester lubricant: The compounds produced in accordance with this invention were blended into a synthetic ester oil lubricant and tested in an oxidation test in accordance with the following procedure.

A sample of the test composition is heated to 450 F. and air at the rate of about 5 liters per hour is passed through for a period of about 24 hours. Present in the test sample are specimens of iron, copper, aluminum, and lead. The kinematic viscosity is measured at 100 F. (percent KV change) and the change in the neutralization number (NN change). It should be noted that the metals are typical metals of engine or machine construction, and they also provide some catalysis for the oxidation of organic materials. The results, tabulated in the following 1 Synthetic ester made from pentaerytluitol and an equimolar mixture of O5 and C9 monocarboxylic acids.

2 Same as oil A, except it contains about 5% of an additive package comprising a menu amount of a neutral phosphate ester and lesser amounts of an amine mixture and metal suppressor, as well as about 0.3% of bis(nonylphenyl)phosphonate.

Extreme pressure properties: In this test, the well-known 4-ball test, an amount of the product of Example 1 sufficient to give 0.04% P was added to the ester identified as A in the above table. The test is run for /2 hour at 390 F. using 52100 steel balls under a load of kg. At 1000 r.p.m. the scar diameter on the test ball was 0.70 mm. The scar diameter on the test ball in the uninhibited lubricant was 2.24 mm. under the same conditions.

I claim:

1. A lubricating oil composition comprising a major amount of a lubricating oil and an amount sufficient to improve the stability properties thereof of a compound produced by a method comprising reacting together cetyl vinyl ether, N-vinylpyrrolidone and a trihydrocarbyl phosphite, wherein in said compound the vinyl reactants form recurring copolymeric units having molecular weights of from about 750 to about 76,000.

2. The composition of claim 1 wherein said compound is present in an amount of form about 0.005 to about 15% by weight of said oil.

3. The composition of claim 1 wherein the compound is prepared in the presence of a free radical initiator.

4. The composition of claim 3 wherein said initiator is ditertiary butyl peroxide.

5. The composition of claim 1 wherein the said lubricating oil is a synthetic ester lubricating oil.

6. The composition of claim 5 wherein the said ester is a pentaerythritol ester.

7. The composition of claim 6 wherein the ester is prepared from pentaerythritol and a monocarboxylic acid having from 1 to about 20 carbon atoms.

8. The composition of claim 6 wherein the acid is a mixture of acids containing from 5 to 9 carbon atoms.

9. The composition of claim 1 wherein equimolar amounts of said cetyl vinyl ether and said N-vinylpyrrolidone are employed.

10. The composition of claim 1 wherein the said phosphite is triethyl phosphite.

References Cited UNITED STATES PATENTS 9/1964 Flowers et a1. 252-499 8/1966 Sims et a1 252-499 US. Cl. X.R. 252--400; 2602 P UTED STATES PATENT QFFECE C.TFICATE EUHN Patent No. 3,663,439 Dated May 16, 1972 In n GERASSIMOS FBANGATOS It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

In column 1, line 5'7, "generaly" should be generally In column 1, formula, that portion of the formula reading N should be H/,N\ clrh c=0 2 i=0 2 In column 2, line 22, "triphentaerythritol" should be tripentaerythritol In column L, line 1? (Claim 2) "form" should be from CH H2 iH Signed and sealed this 2L th day of October 1972.

(SEAL) Attest:

EDWARD M.FLETCHER,JR., ROBERT GOTISCHALK Attesting Officer Commissioner of Patents 272 3 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,663, 9 Dated May 16, 1972 lnv n fl GERASSIMOS FBANGATOS It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

In column 1, line 57, "generaly" should be generally In column 1, formula, that portion of the formula reading l N should be H/\\\ CH O 2 =0 In column 2, line 22, "triphentaerythritol should be tripentaerythritol In column l, line 1? (Claim 2) form" should be from Signed and sealed this ZL th day of October 1972.

(SEAL) Attest:

EDWARD M.FLETCI-IER,JR. ROBERT GOTTSCHALK Attesting Officer Commissioner of Patents 

